The present invention pertains to a chuck for releasably holding a bit or other work performing member attached to the rotary output spindle of a rotary power tool or the like. The term work performing member can include such devices as drill bits and various finishing tools such as grinding and deburring tools, rotary files, milling and boring tools and other rotary devices which include a stem or shank which is releasably connected to a power head which has a rotary output spindle.
A variety of chucks or work performing member holding devices are known for use with rotary power tools as well as machine tools and manually operated tools. In particular, relatively high speed rotary tools for drilling, and so-called finishing work such as grinding, filing and deburring operations require a chuck which is operable to securely hold the work performing member, provide for quick release so that one member may be exchanged for another, and provide accurate alignment of the member with the axis of rotation of the tool output spindle. U.S. Pat. Nos. 3,495,844; 3,762,732 and 3,794,335 disclose examples of prior art types of chucks for relatively high speed rotary tools. U.S. Pat. Nos. 421,718 and 1,649,567 also disclose chucks which have work performing member clamping mechanisms which are similar in some respects to the chuck of the present invention.
The problems associated with prior art chucks which are solved by the present invention are basically related to the fact that none of the known chucks combine all of the desired features of a chuck intended primarily for use with relatively high speed hand held rotary power tools. For example, it is important to provide a chuck which is capable of producing a high clamping force on the work performing member without the use of wrenches or keys, that is, the chuck should be capable of rapid manual operation to clamp or release the work performing member without the use of any tools. It is also important that the work performing member be retained in accurate alignment with the axis of rotation of the rotary drive or output spindle of the tool. Furthermore, it is desirable that there not be any centrifugal forces generated by high speed rotation of the chuck which would tend to lessen the retaining force on the work performing member. These features as well as others are obtained with the present invention as will be appreciated by those skilled in the art upon reading the detailed description in conjunction with the drawing.